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Class: RuboCop::Cop::Naming::RescuedExceptionsVariableName

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::RuboCop::Cop::AutoCorrector, ::RuboCop::Cop::Base, ::RuboCop::ExcludeLimit, NodePattern::Macros, RuboCop::AST::Sexp
Instance Chain:
Inherits: RuboCop::Cop::Base
Defined in: lib/rubocop/cop/naming/rescued_exceptions_variable_name.rb

Overview

Makes sure that rescued exceptions variables are named as expected.

The PreferredName config option takes a String. It represents the required name of the variable. Its default is e.

Note
This cop does not consider nested rescues because it cannot guarantee that the variable from the outer rescue is not used within the inner rescue (in which case, changing the inner variable would shadow the outer variable).

Examples:

PreferredName: e (default)

# bad
begin
  # do something
rescue MyException => exception
  # do something
end

# good
begin
  # do something
rescue MyException => e
  # do something
end

# good
begin
  # do something
rescue MyException => _e
  # do something
end

PreferredName: exception

# bad
begin
  # do something
rescue MyException => e
  # do something
end

# good
begin
  # do something
rescue MyException => exception
  # do something
end

# good
begin
  # do something
rescue MyException => _exception
  # do something
end

Constant Summary

::RuboCop::Cop::Base - Inherited

EMPTY_OFFENSES, RESTRICT_ON_SEND

Class Attribute Summary

::RuboCop::Cop::AutoCorrector - Extended

::RuboCop::Cop::Base - Inherited

.gem_requirements, .lint?,
.support_autocorrect?

Returns if class supports autocorrect.

.support_multiple_source?

Override if your cop should be called repeatedly for multiple investigations Between calls to on_new_investigation and on_investigation_end, the result of processed_source will remain constant.

Class Method Summary

::RuboCop::Cop::Base - Inherited

.autocorrect_incompatible_with

List of cops that should not try to autocorrect at the same time as this cop.

.badge

Naming.

.callbacks_needed, .cop_name, .department,
.documentation_url

Returns an url to view this cops documentation online.

.exclude_from_registry

Call for abstract Cop classes.

.inherited,
.joining_forces

Override and return the Force class(es) you need to join.

.match?

Returns true if the cop name or the cop namespace matches any of the given names.

.new,
.requires_gem

Register a version requirement for the given gem name.

.restrict_on_send

::RuboCop::ExcludeLimit - Extended

exclude_limit

Sets up a configuration option to have an exclude limit tracked.

transform

Instance Attribute Summary

Instance Method Summary

::RuboCop::Cop::Base - Inherited

#add_global_offense

Adds an offense that has no particular location.

#add_offense

Adds an offense on the specified range (or node with an expression) Unless that offense is disabled for this range, a corrector will be yielded to provide the cop the opportunity to autocorrect the offense.

#begin_investigation

Called before any investigation.

#callbacks_needed,
#cop_config

Configuration Helpers.

#cop_name, #excluded_file?,
#external_dependency_checksum

This method should be overridden when a cop’s behavior depends on state that lives outside of these locations:

#inspect,
#message

Gets called if no message is specified when calling add_offense or add_global_offense Cops are discouraged to override this; instead pass your message directly.

#name

Alias for Base#cop_name.

#offenses,
#on_investigation_end

Called after all on_…​

#on_new_investigation

Called before all on_…​

#on_other_file

Called instead of all on_…​

#parse

There should be very limited reasons for a Cop to do it’s own parsing.

#parser_engine,
#ready

Called between investigations.

#relevant_file?, #target_rails_version, #target_ruby_version, #annotate, #apply_correction, #attempt_correction,
#callback_argument

Reserved for Cop::Cop.

#complete_investigation

Called to complete an investigation.

#correct, #current_corrector,
#current_offense_locations

Reserved for Commissioner:

#current_offenses, #currently_disabled_lines, #custom_severity, #default_severity, #disable_uncorrectable, #enabled_line?, #file_name_matches_any?, #find_message, #find_severity, #range_for_original, #range_from_node_or_range,
#reset_investigation

Actually private methods.

#use_corrector

::RuboCop::Cop::AutocorrectLogic - Included

::RuboCop::Cop::IgnoredNode - Included

Constructor Details

This class inherits a constructor from RuboCop::Cop::Base

Instance Method Details

#autocorrect(corrector, node, range, offending_name, preferred_name) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/rescued_exceptions_variable_name.rb', line 96

def autocorrect(corrector, node, range, offending_name, preferred_name)
  corrector.replace(range, preferred_name)
  correct_node(corrector, node.body, offending_name, preferred_name)
  return unless (kwbegin_node = node.parent.each_ancestor(:kwbegin).first)

  kwbegin_node.right_siblings.each do |child_node|
    correct_node(corrector, child_node, offending_name, preferred_name)
  end
end

#correct_node(corrector, node, offending_name, preferred_name) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/rescued_exceptions_variable_name.rb', line 116

def correct_node(corrector, node, offending_name, preferred_name)
  return unless node

  node.each_node(:lvar, :lvasgn, :masgn) do |child_node|
    next unless variable_name_matches?(child_node, offending_name)

    corrector.replace(child_node, preferred_name) if child_node.lvar_type?

    if child_node.masgn_type? || child_node.lvasgn_type?
      correct_reassignment(corrector, child_node, offending_name, preferred_name)
      break
    end
  end
end

#correct_reassignment(corrector, node, offending_name, preferred_name) (private)

If the exception variable is reassigned, that assignment needs to be corrected. Further lvar nodes will not be corrected though since they now refer to a different variable.

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/rescued_exceptions_variable_name.rb', line 134

def correct_reassignment(corrector, node, offending_name, preferred_name)
  if node.lvasgn_type?
    correct_node(corrector, node.child_nodes.first, offending_name, preferred_name)
  elsif node.masgn_type?
    # With multiple assign, the assignments are in an array as the last child
    correct_node(corrector, node.children.last, offending_name, preferred_name)
  end
end

#message(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/rescued_exceptions_variable_name.rb', line 159

def message(node)
  offending_name = variable_name(node)
  preferred_name = preferred_name(offending_name)
  format(MSG, preferred: preferred_name, bad: offending_name)
end

#offense_range(resbody) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/rescued_exceptions_variable_name.rb', line 91

def offense_range(resbody)
  variable = resbody.exception_variable
  variable.source_range
end

#on_resbody(node)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/rescued_exceptions_variable_name.rb', line 66

def on_resbody(node)
  offending_name = variable_name(node)
  return unless offending_name

  # Handle nested rescues by only requiring the outer one to use the
  # configured variable name, so that nested rescues don't use the same
  # variable.
  return if node.each_ancestor(:resbody).any?

  preferred_name = preferred_name(offending_name)
  return if preferred_name.to_sym == offending_name

  # check variable shadowing for exception variable
  return if shadowed_variable_name?(node)

  range = offense_range(node)
  message = message(node)

  add_offense(range, message: message) do |corrector|
    autocorrect(corrector, node, range, offending_name, preferred_name)
  end
end

#preferred_name(variable_name) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/rescued_exceptions_variable_name.rb', line 143

def preferred_name(variable_name)
  preferred_name = cop_config.fetch('PreferredName', 'e')
  if variable_name.to_s.start_with?('_')
    "_#{preferred_name}"
  else
    preferred_name
  end
end

#shadowed_variable_name?(node) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/rescued_exceptions_variable_name.rb', line 165

def shadowed_variable_name?(node)
  node.each_descendant(:lvar).any? { |n| n.children.first.to_s == preferred_name(n) }
end

#variable_name(node) (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/rescued_exceptions_variable_name.rb', line 152

def variable_name(node)
  asgn_node = node.exception_variable
  return unless asgn_node

  asgn_node.children.last
end

#variable_name_matches?(node, name) ⇒ Boolean (private)

[ GitHub ]

  
# File 'lib/rubocop/cop/naming/rescued_exceptions_variable_name.rb', line 106

def variable_name_matches?(node, name)
  if node.masgn_type?
    node.each_descendant(:lvasgn).any? do |lvasgn_node|
      variable_name_matches?(lvasgn_node, name)
    end
  else
    node.children.first == name
  end
end